The present invention relates to a golf club head, more particularly to a hollow structure made of a titanium alloy and a magnesium alloy.
In recent years, large-sized wood-type hollow golf club heads are widely used. The weight of a golf club head naturally has an upper limit, therefore, in the case of a large-sized golf club head, the weight margin which can be utilized to optimize the weight distribution or to adjust the positions of the center of gravity and sweet spot and the like, becomes decreased. Thus, the design freedom with respect to the weight distribution is decreased.
In order to solve such problem, a hybrid hollow golf club has been proposed, wherein the main body of the head which is made of a metal material, is provided in the crown portion with an opening in order to reduce the weight, and the opening is closed by a light-weight FRP cover. Such a metal/FRP hybrid head is excellent at design freedom with respect to the weight distribution. However, since the internal energy loss of FRPs or fiber reinforced resins is very large when compared with metal materials, the ball hitting sound becomes dull, and the tone becomes low, further, the decay becomes fast. Therefore, the ball hitting sound of the hybrid heads is usually not preferred by many golfers.
In the US patent application publication No. US 2006-014592-A1, a hollow golf club head is disclosed, wherein a main body of the club head made of a titanium alloy is provided with an opening, and the opening is covered with a thin plate of a magnesium alloy. In this technique, as the covering plate is not a fiber reinforced resin, a preferable hitting sound may be obtained. But, when the size of the main body is considered, the covering plate is small, therefore, it is difficult to increase the weight margin.